A generalised geometric model for the determination of shear angle during the bias-extension test

The angle between warp and weft yarns of woven fabric changes during the shear mechanism and this behaviour affects the drape, bending, tensile, forming and handle properties of the product. It is therefore important to estimate this shear angle when designing woven fabric. This study aims to propose a new generalised model to estimate the shear angle of fabrics having different sample sizes and different structural properties. An experimental study was designed to investigate both the effect of sample size and structural parameters of fabric on the bias-extension test results. Firstly, five different sample sizes were tested for a defined fabric type. Then, three fabrics having two different weave types and two different settings were tested with two test lengths. The shear angle results found by the new generalised geometric model, the formula is given in the literature and the experimental measurements were compared. The results of the proposed model are close to the measured ones. In addition, it has been observed that fabric properties such as weave type and setting have considerable effects on the shear behaviour of fabrics.